Various treatments are conventionally performed on substrates (substrates to be treated) to produce electronic devices. For example, when the electronic device is a semiconductor, a semiconductor wafer (wafer) is supplied, and then an insulating film or a metal film is grown (film-forming process), a photoresist pattern is formed (photolithography process), the film is processed using the photoresist pattern (etching process), a conductive layer is formed on the semiconductor wafer (impurity-adding process; also referred to as doping or diffusion process), and the uneven surface of the film is polished to be flat (CMP (chemical mechanical polishing) process). After these processes, a semiconductor wafer electrical property test is conducted to check the finish of the pattern and the electrical properties. (These processes are also generically referred to as “the pre-process.”) Thereafter, semiconductor chips are formed (post-process).
In addition to the above processes, the pre-process includes a cleaning process using plasma, ozone, ultraviolet rays, etc.; a photoresist-pattern removal process using plasma, radical-containing gas, etc. (also referred to as ashing or incineration removal); and other processes. Examples of the film-forming process include CVD, by which a film is formed by chemical reaction with reactive gas on the wafer surface, and sputtering, by which metal films are formed. Examples of the etching process include dry etching by chemical reaction in plasma and etching by ion beam. Plasma refers to gas in an ionized state in which ions, radicals, and electrons are present.
In the pre-process, the wafer in-plane uniformity of each treatment is important for the following reason. Since a plurality of semiconductor chips are formed on a semiconductor wafer, if the in-plane uniformity deteriorates, this causes variation in the performance of each chip, and affects the yield. Accordingly, the in-plane uniformity of each treatment is confirmed by a method in which the above treatments are performed separately, and the wafer in-plane uniformity of each treatment is evaluated. Then, the process conditions are optimized. The uniformity of plasma itself can be evaluated by, for example, a method in which a Langmuir probe is placed in the apparatus to measure the physical constants of the plasma. The variation in the space is evaluated by sweeping the probe position. Alternatively, there is a method in which the generated plasma is analyzed by using emission spectrometry to measure excited species generated in the plasma. The distribution in the space in each field of view is evaluated by changing the measurement field of view.